Why is my laptop not turning on

Okay, This laptop used to work until someday I closed the screen and opened it it was still working but nothing shown on the screen, shut it down that it didn't turn on again, when I put the charger the power led light but it doesn't turn on, when I take out the battery and put the charger it does nothing, so I followed a tutorial and washed the motherboard and it worked and did some tests than when it restarted it did the same thing, fan spinning fast and when I shut it down it doesn't turn on again, did the same thing and it worked than I accidentally closed the screen and it's down now, what would cause that and how to fix it. thanks.

Note: there were some marks of a dry sticky liquid on the MB.